This invention relates generally to compressors and, in particular, to an improved lubrication system for a compressor unit.
A conventional compressor unit comprises a compressor housing having a crank chamber, a suction chamber and a discharge chamber, a cylinder block having a plurality of cylinders mounted in the compressor housing, pistons means slidably fitted within the cylinders, a front housing on the compressor housing including an opening as a shaft seal cavity for receiving a drive shaft, the drive shaft rotatably borne in the front housing through the shaft seal cavity, a crank disposed in the crank chamber for converting the rotating motion of the drive shaft into reciprocating motion to impart the reciprocating motion to the pistons, and suction and discharge valve means for controlling the flow of fluid between the suction chamber and each cylinder and between the discharge chamber and each cylinder.
In the conventional refrigerant compressor, a charge of refrigerant gas and lubricating oil is introduced. In the operation of the compressor, while the refrigerant gas is compressed by pistons reciprocating within corresponding cylinders, moving parts of the compressor must be lubricated by the lubricating oil.
The oil passes into the crank chamber together with the refrigerant gas as a blow-by gas through a gap between the piston and the inner wall of the corresponding cylinder to lubricate therebetween. The oil is separated from the refrigerant gas in the crank chamber and lubricates moving parts therein. A passageway or a balance hole is provided to return the refrigerant gas in the crank chamber to the suction chamber.
To lubricate a shaft seal assembly disposed within the shaft seal cavity and mounted on the drive shaft, an oil passageway is provided for communicating between the crank chamber and the shaft seal cavity.
A lubrication system for a compressor unit is disclosed in U.S. Pat. No. 4,005,948 to Hiraga wherein a deflector is formed depending from the inner wall of the compressor for collecting and then directing oil splashed onto the inner wall to a port or oil hole formed in the front housing in communication with the shaft seal cavity. Thus, the lubricating oil circulates between the crank chamber and the shaft seal cavity lubricating the shaft seal, bearings, and other moving parts.
But, in the arrangement disclosed in the Hiraga patent, the oil is not sufficiently used for lubricating moving parts because all oil collected and directed to the oil hole by the deflector does not flow into the oil hole but a part of the collected oil leaks into the crank chamber.
Moreover, to prevent the oil in the crank chamber from flowing into the balance hole in order to minimize the outflow of lubricating oil from the compressor, some constructions of the opening of the balance hole have been proposed. But these proposed constructions are comparatively complicated and make the compressor unit difficult.